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A gravity survey of Islay, Scotland

Published online by Cambridge University Press:  01 May 2009

E. M. Durrance
E. M. Durrance
Affiliation:
Department of Geology, University of Exeter, Exter, Devon
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Summary

The results of a gravity survey of Islay indicate that, with respect to a local Bouguer anomaly datum of 260 g.u., a positive anomaly of 100 g.u. occurs over the Lewisian gneiss of the Rhinns of Islay, and, immediately to the E, a negative anomaly of —120 g.u. occurs S of Bowmore. Both anomalies trend N—E to S—W. The negative anomaly is interpreted as due to the presence of a structural basin occupied by a maximum 4600 m of Bowmore Sandstones and Dalradian meta-sediments. The boundary between the Lewisian gneiss and this basin is the Loch Indaal fault. At the head of Loch Indaal this fault bifurcates, one branch continuing north-eastwards as the Bonahaven fault, the other trending northwards as the Loch Gruinart fault, All the faults are considered to possess transcurrent components. The stratigraphic position of the Bowmore Sandstones is similar to that of the supposed Torridonian sediments of western Islay.

Type
Articles
Information
Geological Magazine , Volume 113 , Issue 3 , May 1976 , pp. 251 - 261
Copyright
Copyright © Cambridge University Press 1976

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